Color printer and printing method using the same

1. A color printer provided with ink jet heads comprising three trains of nozzle holes for respectively discharging different colored inks, each train of nozzle holes composed of a plurality of nozzle holes which are arranged at intervals of three pitches in an auxiliary scanning direction, and the nozzle holes of the three trains of nozzle holes are disposed at equal intervals in a main scanning direction while shifting every one pitch in the auxiliary scanning direction wherein said different colored inks are discharged and sequentially superimposed over one another on a recording medium to synthesize colors so as to make a color print; wherein the color printer further comprises control means for controlling the ink jet heads to make a print which is regular in sequence of superimposition of colors in the manner of; discharging only one colored ink through the nozzle hole of a first train of nozzle holes which is any one of the three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction in a first step; discharging ink through the nozzle holes of the first train of nozzle holes and the nozzle holes of a second train of nozzle holes adjacent to the first train of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a second step; discharging ink through all nozzle holes of the first, second and remaining third trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a third step; discharging ink through all nozzle holes of the second and third trains of nozzle holes and only through the last nozzle hole of the first train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fourth step; discharging ink through all nozzle holes of the third train of nozzle holes and only through the last nozzle holes of the first and second trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fifth step; discharging ink through all nozzle holes of the first train of nozzle holes and only through the first nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by (n-1).times.3+1 pitches (n is the number of nozzle holes of each nozzle train) in the auxiliary scanning direction relative to the recording medium in a sixth step; discharging ink through all nozzle holes of the first and second trains of nozzle holes and only through the first nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a seventh step; executing printing operations sequentially in the third to seventh steps; discharging ink only through the last nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a step following the fifth step when ending the printing; and then discharging ink only through the last nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium while the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium so as to end the printing.

2. A color printer provided with ink jet heads comprising three trains of nozzle holes for respectively discharging different colored inks, each train of nozzle holes composed of a plurality of nozzle holes which are arranged at intervals of three pitches in the auxiliary scanning direction, and the nozzle holes of the three trains of nozzle holes are disposed at equal intervals in the main scanning direction while shifting every one pitch in the auxiliary scanning direction wherein said different colored inks are discharged and sequentially superimposed over one another on a recording medium to synthesize colors so as to make a color print, wherein the color printer further comprises: first control means for controlling the ink jet heads to make a print which is regular in sequence of superimposition of colors in the manner of; discharging only one colored ink through the nozzle hole of a first train of nozzle holes which is any one of the three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction in a first step; discharging ink through the nozzle holes of the first train of nozzle holes and the nozzle holes of a second train of nozzle holes adjacent to the first train of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a second step; discharging ink through all nozzle holes of the first, second and remaining third trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a third step; discharging ink through all nozzle holes of the second and third trains of nozzle holes and only through the last nozzle hole of the first train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fourth step; discharging ink through all nozzle holes of the third train of nozzle holes and only through the last nozzle holes of the first and second trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fifth step: discharging ink through all nozzle holes of the first train of nozzle holes and only through the first nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by (n-1).times.3+1 pitches (n is the number of nozzle holes of each nozzle train) in the auxiliary scanning direction relative to the recording medium in a sixth step; discharging ink through all nozzle holes of the first and second trains of nozzle holes and only through the first nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a seventh step; executing printing operations sequentially in the third to seventh steps; discharging ink only through the last nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a step following the fifth step when ending the printing; and then discharging ink only through the last nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium while the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium so as to end the printing; second control means for controlling the ink jet heads to make a print which is irregular in sequence of superimposition of colors by discharging ink through all nozzle holes to make a print on the recording medium while prohibiting ink from being discharged through respective first nozzle holes of the two trains of nozzle holes of the three trains of nozzle holes in the auxiliary scanning direction as the ink jet heads are scanned in the main scanning direction, then discharging ink through all nozzle holes to make a print on the recording medium while prohibiting ink from being discharged only through the first nozzle hole of either of the two trains of nozzle holes in the auxiliary scanning direction as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium, and thereafter discharging ink through all nozzle holes of the three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium; and selection means for selecting either the first control means or the second control means to control the ink jet heads when the printing is performed.

3. The color printer according to claim 2, wherein the selection control means selects either the first control means or the second control means when an external operation member is operated.

4. The color printer according to claim 2, wherein the selection control means includes printing mode judgement means for selecting the printing mode of the print data is a photographic mode or a graphic mode, and for selecting the second control means if the printing mode is the photographic mode and selecting the first control means if the printing mode is the graphic mode in response to the result of judgement.

5. The color printer according to claim 2, further comprising a test pattern memory for storing therein test pattern data and test pattern printing means for reading the test pattern data from the test pattern memory to cause the control means selected by the selection means to control the ink jet heads to make a print.

6. The color printer according to claim 5, further comprising mode selection means for selecting a test mode for printing the test pattern and a normal printing mode for printing normal print data.

7. A printing method using a color printer provided with ink jet heads comprising three trains of nozzle holes for respectively discharging different colored ink, each train of nozzle holes being composed of a plurality of nozzle holes which are arranged at intervals of three pitches in an auxiliary scanning direction, and the nozzle holes of the three trains of nozzle holes are disposed at equal intervals in a main scanning direction while shifting every one pitch in the auxiliary scanning direction wherein different colored inks are discharged and sequentially superimposed over one another on a recording medium to synthesize colors so as to make a color print, the method comprising the following steps for making a print which is regular in sequence of superimposition of colors; discharging only one colored ink through the nozzle holes of a first train of nozzle holes which is any one of three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction in a first step; discharging ink through the nozzle holes of the first train of nozzle holes and the nozzle holes of a second train of nozzle holes adjacent to the first train of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a second step; discharging ink through all nozzle holes of the first, second and remaining third trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a third step; discharging ink through all nozzle holes of the second and third trains of nozzle holes and only through the last nozzle hole of the first train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fourth step; discharging ink through all nozzle holes of the third train of nozzle holes and only through the last nozzle holes of the first and second trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fifth step; discharging ink through all nozzle holes of the first train of nozzle holes and only through the first nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by (n-1).times.3+1 pitches (n is the number of nozzle holes of each nozzle train) in the auxiliary scanning direction relative to the recording medium in a sixth step; discharging ink through all nozzle holes of the first and second trains of nozzle holes and only through the first nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a seventh step; executing printing operations sequentially in the third to seventh steps; discharging ink only through the last nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a step following the fifth step when ending the printing; and then discharging ink only through the last nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium so as to end the printing.

8. A printing method using a color printer provided with ink jet heads comprising three trains of nozzle holes for respectively discharging different colored ink, each train of nozzle holes being composed of a plurality of nozzle holes which are arranged at intervals of three pitches in the auxiliary scanning direction, and the nozzle holes of the three trains of nozzle holes are disposed at equal intervals in the main scanning direction while shifting every one pitch in the auxiliary scanning direction wherein different colored inks are discharged and sequentially superimposed over one another on a recording medium to synthesize colors so as to make a color print, the method comprising: a first printing method of making a print which is regular in sequence of superimposition of colors, said method composed of steps of: discharging only one colored ink through the nozzle hole of a first train of nozzle holes which is any one of three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction in a first step; discharging ink through the nozzle holes of the first train of nozzle holes and the nozzle holes of a second train of nozzle holes adjacent to the first train of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a second step; discharging ink through all nozzle holes of the first, second and remaining third trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a third step; discharging ink through all nozzle holes of the second and third trains of nozzle holes and only through the last nozzle hole of the first train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fourth step; discharging ink through all nozzle holes of the third train of nozzle holes and only through the last nozzle holes of the first and second trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a fifth step; discharging ink through all nozzle holes of the first train of nozzle holes and only through the first nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by (n-1).times.3+1 pitches (n is the number of nozzle holes of each nozzle train) in the auxiliary scanning direction relative to the recording medium in a sixth step; discharging ink through all nozzle holes of the first and second trains of nozzle holes and only through the first nozzle hole of the third train of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a seventh step; executing printing operations sequentially in the third to seventh steps; discharging ink only through the last nozzle holes of the second and third trains of nozzle holes in the auxiliary scanning direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium in a step following the fifth step when ending the printing; and then discharging ink only through the last nozzle hole of the third train of nozzle holes in the auxiliary direction to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium so as to end the printing; and a second printing method of making a print which is irregular in sequence of superimposition of colors, said method being composed of steps of discharging ink through all nozzle holes to make a print on the recording medium while prohibiting ink from being discharged through respective first nozzle holes of the two trains of nozzle holes of the three trains of nozzle holes in the auxiliary scanning direction as the ink jet heads are scanned in the main scanning direction, then discharging ink through all nozzle holes to make a print on the recording medium while prohibiting ink from being discharged only through the first nozzle hole of either of the two trains of nozzle holes in the auxiliary scanning direction as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium, and thereafter discharging ink through all nozzle holes of the three trains of nozzle holes to make a print on the recording medium as the ink jet heads are scanned in the main scanning direction while they are shifted by one pitch in the auxiliary scanning direction relative to the recording medium; and wherein the first control method or the second control method is arbitrarily or automatically selected to make a print.

9. The printing method using the color printer according to claim 8, further comprising a step of selecting the first printing method or the second printing method by detecting an operation of an external operation member.

10. The printing method using the color printer according to claim 8, further comprising a step of selecting the first printing method or the second printing method based on the control data from a host.

11. The printing method using the color printer according to claim 8, further comprising steps of judging whether a printing mode of print data is a photographic mode or a graphic mode, and of selecting the second printing method if the printing mode is the photographic mode and of selecting the first printing method if the printing mode is the graphic mode.